Improvement in lifting-jacks



L. OHARA.

Lifting-Jack.

Patented June 8, 1875.

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UNITED STATES PATENT QFFIGE.

LEWIS OHARA, OF OSWEGO, NEW YORK.

IMPROVEMENT IN LlFTlNG-JACKS.

Specification forming part of Letters Patent No. 164,32 3, dated June 8, 1875; application filed May 20, 1875.

To all whom it may concern:

Be it known that I, LEWIS OHARA, of Oswego, county of Oswego and State of New York, have invented an Improved Lifting Jack, of which thefollowing is a specification, reference beinghad to the accompanying drawin gs forming part hereof.

My invention consists in the combination, in a lifting-jack, of a hollow standard or post, in which is arranged to slide a bar or rod, whichis supported and raised and lowered by a hand-lever, to which it is connected by rods pivoted to it, one on each side, and to the bifurcated short arm of the hand-lever, which hand-lever is pivoted upon a slide arranged to be raised or lowered on the standard by means of a male screw on the standard, and a female screw in the slide, whereby the lever and sliding rod may be adjusted at any desired height upon the standard, and whereby, when the hand-lever is forced downward in raising a weight upon the upper end of said rod, and the bifurcated short arm is brought past the center of the standard, the weight sustained upon the rod will act to lock the lever in position to support the rod.

Figure 1 is a side elevation of my liftingjack, and Fig. 2 is a longitudinal central sectional view of the same.

S is the standard or post, made preferably cylindrical and hollow, as shown. B is the rod or bar, arranged to slide in the hollow standard, as shown. L is the hand-lever, pivoted upon the slide 8 at (Z, as shown, and having the long arm a and the bifurcated small arm a. O 0 are connecting-rods, pivoted to the head of the rod B, one on each side at c, and pivoted one to each of the bifurcations of the short arm a of the lever Lat c. The slide 8 is provided with a female screw, as shown, arranged to work on the male screw 1), formed on the standard S.

N ow, it is evident that by means of the screwslide 8 working on the male screw b, the lever L and the sliding rod may be adjusted at any desired height upon the standard S. It is also evident that when the lever L is forced downward in raising a weight upon the head of the rod R, and the bifurcated short arm a is brought past the center of the standard S into the position shown in Fig. 2, the weight sustained upon the rod R will act, by its pressure upon the connecting-rods G O, to press the short arm a outward, and hence to press the long arm ainward against the standard, and thus lock the lever L in position to support the rod R and its sustained weight.

What I claim as my invention, and desire to secure by Letters Patent, is

The combination, in a lifting-jack, of the hollow standard S, with its male screw 12, the rod R, the lever L, with its bifurcated short arm a, the connecting-rods U C, and the screwslide 8, as described.

LEWIS OHARA. Witnesses: 7

WILLIAM H. KENYON, CHAS. W. PRATT. 

